This invention relates to improvements in a cordless rotational coupling device for a dental instrument having a built-in battery which enables a dentist to disconnect a battery housing from a motor housing or to rotatably join them easily and quickly.
In the dental handpiece having a built-in battery, it has been necessary to disconnect the built-in battery independently of a drive motor in order to either charge the battery or to exchange the worn out battery with a new one. The coupling device between the motor housing and the battery housing is so complicated that it is very difficult to disassemble or assemble them quickly.